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Botany. — "Some observations on the longitudinal growth of stems 

 and flower-stalks" . ^j Prof. E. Verschaffelt. (Communicated 

 by Prof. Hugo de Vries). 



(Communicated in the meeiing of March 25, 1905). 



Superficial observation already shows that in many cases the 

 growth of stems, leaf- and flower-stalks is greatly dependent on the 

 organs which they bear: buds, leaf-lamina, flowers. When these 

 latter are removed the growth of the axial parts is generally arrested 

 and they even die after a shorter or longer time. 



In literature I have not found any investigations mentioned, 

 attempting to analyse this phenomenon more closely; e.g. in the 

 case of flower-stalks, to find out whether excision of cei'tain parts of 

 the flow^er had as much influence on the growth of the stalk as the 

 removal of the entire flower. I have now been able to make this 

 out for some vernal plants by measurements of growtli and I shall 

 in what follows give a short account of the results. 



1 chose preferably flowers for this purpose, since here at the top 

 of the same spindle organs of different physiological functions occur 

 together and so the experiments admitted of greater variety. In one 

 case, that of Eranthis hiemalis Salisb., I shall describe the course 

 of the investigation and its results a little more in extenso; the 

 other examples will be more briefly dealt with. 



The stem of Eranthis, as will be known, bears at its top a single 

 flower and close under it, united to a sort of broad collar, a \vhorl 

 of three green sitting parted leaves. As long as the stem is still 

 under the ground, its top is sharply bent downward and the still 

 perfectly closed flower hangs down, protected by the three leaves, 

 still vellow then, which envelop it. As soon as the top of 

 the stem has come above the ground ;\jrI also the flower has 

 come free, this latter raises and soon unfolds itself; tlien the basal 

 collar spreads out and turns green. The measin-ements of growth 

 were made in the stage lietween the period when the stem is not 

 yet visible abo\'e the ground and that, in which, after the petals 

 and stamens have fallen off, oidy the fertilised pistils remain. About 

 this time the longitudinal growtli stops. Whether afterwards, during 

 the ripening of the fruits, a new period of growth l)egins, as in 

 other plants, I have not investigated. 



The plants, serving for the investigation, were placed in a hothouse 

 of the Botanical Garden at Amsterdam, in which the mean tempe- 

 rature was 20^ C. and ij] which the specimens developed very rapidly 

 and entirely normally. 



